Fix inexistent devcontainer image - from jammy to nobel

[vncoelho]

Current image does not exist. Correct image is fixed in the PR

[vncoelho]

The command could not be loaded, possibly because:
  * You intended to execute a .NET application:
      The application 'format' does not exist.
  * You intended to execute a .NET SDK command:
      A compatible .NET SDK was not found.

Requested SDK version: 9.0.100
global.json file: /workspaces/neo/global.json

Installed SDKs:
9.0.100-rc.2.24474.11 [/usr/share/dotnet/sdk]

Install the [9.0.100] .NET SDK or update [/workspaces/neo/global.json] to match an installed SDK.

Learn about SDK resolution:
https://aka.ms/dotnet/sdk-not-found

Still, perhaps this version is not compatible with global requirements

[vncoelho]

But maybe 9.0.100-rc.2.24474.11 is enough for our tests.
Relaxing global to 9 worked here.

{
  "sdk": {
    "version": "9",
    "rollForward": "latestFeature",
    "allowPrerelease": false
  }
}

I think the PR is good for now

[vncoelho]